A great variety of connectors are used for connecting cables of various types with terminals of various types. Such connectors each have (1) a connecting portion 14 by which the connector removably engages a terminal (e.g., an automotive battery terminal or the like) and (2) a cable-attachment portion by which the cable is permanently assembled with the connector, at the appropriate time, so that the cable thereafter can easily and removably be electrically connected to a terminal.
Attaching a cable to the cable-attachment portion of such a connector is carried out in a variety of ways--e.g., crimping, soldering, winding, bolting, etc. Various attachment means and methods used have a number of drawbacks and problems, particularly with respect to the specific field of this invention--connectors for automotive-type multi-strand cable.
As used herein, the term "automotive-type" refers to battery connectors for self-propelled vehicles of various kinds, including but not limited to vehicles powered by internal combustion engines or by battery power, or by any combination of the two (including, e.g., automobiles, trucks, planes, fork-lifts and carts, boats, locomotives or the like), and also refers to connectors used in conjunction with stationary batteries such as those associated with stand-by power supplies.
As used herein, the term "battery" refers to a storage device for electrical energy, typically embodied in the common automotive-type lead-acid battery, but which also includes other battery chemistries (e.g., lithium polymer, nickel-cadmium and the like), fuel cells, photovoltaic-battery combination and the like.
Soldering is one method used for attachment of multi-strand automotive-type cable to battery connectors. Such soldering attachment involves a number of common steps, typically including introducing molten solder or solder pellets at the point or area of attachment and bringing the multi-strand cable and connector into simultaneous contact with molten solder. The process is time-consuming and often inconsistent, and can result in varying attachments of widely-varying strength and reliability and in some cases varying electrical consistency. The process also carries with it certain risks involving the molten solder.
During use, automotive-type battery connectors of the prior art can in some cases experience strain on the part of the cable which is immediately adjacent to the connector--i.e., the part adjacent to the portion of the cable which is used for attachment to the battery connector. The strains imposed on the cable by any repetitive bending action can weaken the cable and its attachment to the connector.
Soldered attachment of a multi-strand cable to a connector using what might be referred to as "pre-positioned" solder has published in the past. This is seen in the disclosure of U.S. Pat. No. 1,188,055 (Faile). However, such device would be prone to have significant problems which would render it unacceptable, as hereafter explained.
For one thing, the Faile connector has a cable-attachment cavity in which the diameter of the open end is smaller than the diameter of the inner end, a feature intended to prevent the solder from falling out before attachment of the cable with the connector. A significant shortcoming of the Faile device is that a thorough connection cannot be formed between the cable and the internal surfaces of the cavity--i.e., the end and the sidewalls of the cavity. Such an incomplete connection can lead to electrical and structural deficiencies. The configuration will result in air pockets or voids adjacent to surfaces of the multi-strand cable--surfaces therefore wasted in that they then fail to provide electrical pathways otherwise possible. Furthermore, internal surfaces of the Faile cable-receiving cavity are not protected from accumulation of contaminates and are not protected from corrosion, and such surface problems may then degrade effectiveness of the electrical union at surfaces of attachment. Not only would the electrical connection be wanting, but "cold solder" problems could result and structurally weak connections would result given that only a small portion of the end of the cable would be joined to the solder. Over time, such connection can more readily break, thereby allowing the cable to be pulled from the connector.
In summary, in the prior art a number of very significant disadvantages exist with respect to soldered and other attachment of multi-strand automotive-type cable to automotive-type connectors, and a need exists for substantial advances.
While the specific field of automotive-type battery connectors has its own specific problems and concerns, particularly with respect to permanent attachment of multi-strand cable to such connectors by soldering, it should be noted that various devices involving pre-placed solder exist in the more general field of connectors for connecting electrical wire to terminals. Prior connectors to which single-strand wire is attached by soldering using pre-placed solder, including connectors for use in radio, television and computer applications and the like, are disclosed in various United States patents.
For example, U.S. Pat. No. 3,519,982 (White, Jr.) discloses the use of pre-placed solder in conjunction with small wires in a process which also involves crimping. These devices, which are designed for use with small conductors about 1/0 gauge (0.351 inch diameter) down to about 40 gauge (0.00314 inch diameter), involve the use of solder paste spread along the inner surface of the connector. In conjunction with the crimping of the connector around the cable, heat is applied to the connector thereby melting the solder and reinforcing the attachment. While useful for small conductors, such an attachment is not useful for automotive-type multi-strand electrical cables and connectors.
U.S. Pat. Nos. 3,243,211 (Wetmore) and 3,316,343 (Sherlock) disclose connectors that are made of fusible materials that melt around the cable. These connectors may also employ pre-positioned solder to aid in attaching the cable to the connector. A major shortcoming of these devices is that the fusible connectors are not large enough or strong enough to contain multi-strand automotive-type electrical cables.
U.S. Pat. No. 5,281,167 (Le et al.) discloses a connecting device which utilizes solder that is held in position by a flange. Such a flange restricts the opening of the connector thereby limiting the diameter size of the cable to be attached.
A connector facilitating easy, permanent attachment thereto of automotive-type multi-strand electrical cable would be an important improvement in the art.